Right-click the cells you are referencing, and the cell you are doing your
calculation in. Select Format Cells. are any of those cells formatted as
Text? Format as General and try again.
Most likely is that your formula cell was earlier (unknown to you of course)
pre-formatted as TEXT. Reformat the cell to either general or number (via
clicking Format>Cells ..), and then reconfirm the formula, ie: click inside
the formula bar, press ENTER, and all would be well.
Another possibility, albeit remote, is that you are in formula view. Press
CTRL+` to toggle it back to normal. The ` key is the one just to the left of
the "1" on your keyboard.
Yes, the quotes were only in the post. The first response helped - apparently
somewhere in the field of cells there was a cell formatted as text instead of
numeric even though I thought I had the whole thing formatted as numbers.